screensaver occasionally stops running (squeeze, gnome)
My Gnome (Debian Squeeze) screensaver occasionally stops working. It happens every few days (2? 4-5? It doesn't appear to be regular). Toggling the state of the Power Manager Inhibit Applet (inhibit sleep then re-enable sleep) will fix it (also a reboot will fix it).
The problem is that the screensaver just never activates. I'm using the Pictures screensaver, and it's set to turn on after 1 minute of idle time. I've tried closing all programs and killing many processes (as many as I could without killing the X session) without success. (I *think* that restarting the X session doesn't fix the issue but it's been a while since I've tried that and I'm not in the error condition right now to try to verify that statement.) Changing the selected screensaver from Pictures to something else doesn't fix the issue. Killing the gnome-screensaver process and restarting it doesn't fix the issue. There's no evidence of the screensaver failing to start in .xsession-errors or Xorg.0.log. After the problem occurs I've tried unplugging my only accessory (a wireless USB mouse) but that doesn't fix the issue.
Although the Inhibit Applet workaround is useful, it's still frustrating to have to deal with that, and it only helps after I notice the issue has occurred (i.e. I can't walk away from the computer and be assured the screensaver will turn on).
Has anyone heard of an issue like this? Or know what package to file a bug against? Or know where to look to understand what's happening?